Cosa - Middle Ages

Middle Ages

Cosa appears in some documents dating from the 11th century, although a 9th-century occupation is suggested by frescoes at the abbey of S. Anastasio alle Tre Fontane in Rome, recording the capture of the site by Charlemagne and Pope Leo III. By the end of the 10th century, a small cemetery was found next to a church built over a temple facing the forum. The town is recorded as Ansedoniam civitatem in a privilege of Pope Gregory VII (1073-1085).

Occupation of the site began with a few sunken-floored buildings, but by the 11th century it was concentrated on the Eastern Height, now surrounded by a double bank and ditch. In the 12th century, a tower was built in the centre of these fortifications, with a large cistern on two sides. That this cistern was subsequently used as a prison is suggested by graffiti on its plaster lining, one of which gives the date of 1211.

The castle, belonging to the Aldobrandeschi family in 1269, was destroyed by the Sienese army in 1329, on the pretext that it was occupied by bandits. A catapult or trebuchet base found on the Eastern Height may have formed part of the defences at this time. The site remained deserted after this time.